Lago

Open-source metering and usage-based billing API for SaaS teams. Ingests raw usage events, converts them into charges, and supports flexible pricing models including consumption-based, prepaid credits, and hybrid plans that combine subscriptions with usage. Designed so engineering and product teams can iterate on pricing without rebuilding billing from scratch.

Trusted by companies such as Mistral AI, PayPal, and 1NCE for complex billing at scale. Lago differentiates by being fully open-source and payment-agnostic, offering transparency and control where traditional billing systems operate as black boxes. Deploy self-hosted on your infrastructure or use the managed cloud.

Main capabilities:

• Usage metering API for events, credits, tokens, compute, or API calls at high throughput
• Hybrid plans mixing subscriptions with usage-based pricing, custom contracts, entitlements, and coupons
• Billing and invoicing with dunning and cash collection workflows
• Integrations with payment providers, accounting systems, CRMs, and ERPs
• Self-hosted or cloud deployment, SOC 2 Type II, RBAC

Well suited for AI and ML products metering tokens or inference, enterprise SaaS with complex packaging, IoT and telco billing, and finance teams managing multi-geography invoicing. Developers integrate via REST API and SDKs, while product and finance teams manage plans and pricing through the visual UI.